Sir Richard Branson aims to bring space travel within the reach of ordinary people by pioneering space flights at affordable prices.

The thrill-seeking entrepreneur told Guardian Unlimited that Virgin was investing money in "trying to make sure that, in the not too distant future, people from around the world will be able to go into space". He said he hoped to be a passenger on one of the first tourist space flights into space.

Sir Richard refused to be drawn on details of the project, but said the public should expect an announcement revealing Virgin's latest enterprise at some time in the next two or three weeks.

"All will be revealed over the next two or three weeks - but, in a general sense, space is the ultimate frontier, and something we at Virgin have dearly wanted to do is to bring space tourism one day to the masses," he said.

Space expert Greg Klerkx, author of the book Lost in Space: The Fall of Nasa and the Dream of a New Space Age, said that, for some time, there had been rumours Sir Richard was very interested in space flight.

"He has had some conversations with [space tourism firm] Space Adventures about being a space tourist himself," Mr Klerkx told Guardian Unlimited.

Virgin has long been involved in promoting the adventurous exploits of its chairman and his fellow adventurer Steve Fossett, including the successful Global Challenger mission to fly a balloon non-stop around the world.

Sir Richard's forthcoming announcement could be related to plans for a June 21 test flight of SpaceShipOne, a rocket-propelled reusable space vehicle created by aerospace designer Burt Rutan, of California firm Scaled Composites.

Mr Rutan is already working with Sir Richard on Global Flyer, a bid to make the first solo circumnavigation of the world in a specially-designed, ultra-lightweight jet plane. Sir Richard is acting as reserve pilot.

The ship will be released from a carrier craft at a height of 15,000 metres, and will fire its rockets to climb to a height of 100km before falling back into the atmosphere and gliding to Earth. Mr Klerkx said he was not surprised at talk of a link between Virgin and Scaled Composites' sub-orbital spaceflight plans, currently being bankrolled by billionaire Microsoft co-founder Paul Allen's investment firm, Vulcan Ventures.

"Tier One's first flight is causing a big buzz in the alternative space community, because there has been talk for some time about a cheap but cheerful craft that could go into space. Paul Allen tends not to invest in too many silly things," he said.

Sir Richard would not say whether Virgin's plans involved Scaled Composites' project. "I won't go any further at the moment - but I'd love to talk to you about it in a couple of weeks' time," he said.

On the Tier One website, Mr Rutan said: "Our goal is to demonstrate that non-government manned space flight operations are not only feasible, but can be done at very low costs."

The race to create the first viable space tourism programme has been hotting up since the 1996 announcement of the X Prize, a $10m (£5m) award for the first team managing to privately finance, build and launch a spaceship that can carry three people 100 kilometres above Earth, bring them back safely, and repeat the exercise within two weeks.

Twenty-four teams from seven countries, including three UK-based firms, have registered for the challenge, as well as Scaled Composites' Tier One project.

In 2002, US consulting firm Futron calculated the market for commercial space travel could be worth more than $1bn a year by 2021.

Space Adventures has already created two non-professional astronauts. US businessman Dennis Tito became the first space tourist in 2001, and was followed by South African millionaire Mark Shuttleworth a year later. Both paid a reported fee of around $20m for the privilege.

Another US businessman, Greg Olsen, is due to join this super-rich band of space tourists next year, and Space Adventures hopes to begin ticketed journeys for sub-orbital spaceflights in 2005 or 2006.

"With sub-orbital [spaceflight] you get into space - you can see black above and you get a bit of weightlessness but you don't have the same challenges of fuel and re-entry as you do with orbital," Mr Klerkx said.

He estimates that, if enough people can be persuaded to buy tickets for sub-orbital flights, the cost of tickets could drop to around $10,000 - "the cost of a cruise or some extreme adventures such as climbing Mount Everest. There are big markets for that kind of stuff".

However, not everyone is convinced that space tourism can become a fully-fledged part of the travel industry.

Andrew Nahum, the senior curator of aeronautics at the Science Museum and visiting professor in vehicle design at the Royal College of Art, said he doubted it would ever become a profitable enterprise.

"You have got to put it in proportion - what you are doing is something more ambitious than Concorde. Even that was too expensive and never made a buck."

The discomforts of space travel - which could include dealing with zero gravity, vacuum toilets and space sickness - could also put the average well-heeled traveller off the idea, particularly if a large price tag was attached, he said.

"It's not a volume market ... tourism is the wrong word - it would be more like an extreme sport."